Purification of bast fiber



15 will become apparent during the course of the foltion is conducted under pressure and the material Patented Dec. 4, 1934 ruarrrcsrrou or BAST men Francis H. Snyder, New York, N. Y., assignor 'to Francis H.--Snyder, Inc, New York, N. Y., a corporation of Deiaware I No Dra. Application January 23, 1934,

- Serial No. 708,003

' 14 Claims. (01. 92-12) This invention relates to the purification of duced into the digester a treating solution combast fibers and more particularly to the degumprising an aqueous solution of a soluble sulfite, ming of such fibers as ramie, sisal, flax, jute and which may be either a normal sulfite or a bisulthe like, and especially pita. fite, and a non-carboxylic fatty detergent. The

The principal object of this invention is to protreating solution may or may not contain a solu- 9 vide an efficient and economical process of purible thiosulfate. The treating solution is circufying crude bast fibers, especially for the purpose lated through the fibrous material in the digester of rendering them suitable for use as textile fibers. by drawing the liquor off from the lower portion An important object of the invention is to proof the digester and returning it through a suitable 10 vide asimple, economical and commercially pracspray on to the top of themes of material in ticable process of converting crude pita into purithe digester. During the treatment, the contents fied fibers suitable for use in'the manufacture of of the digester are heated at an elevated temtextiles and paper. perature, preferably above the boiling point of Other objects and advantages of the invention water. In preferred practice, the heating operalowing description. is subjected to the treatment at a temperature I have discovered that strong, substantially of approximately 165 C. After the fibrous matesnow-white fibers suitable for use in the man'ufacrial has been treated in this manner for from apture of paper and particularly for use as textile proximately one to two hours, the treating solu- 20 fibers may be prepared from crude bast fibers by tion is withdrawn from the digester and the stock subjecting the latter to the joint action of a solu- ,is thoroughly flushed with fresh water for the ble sulfite (either a normal sulfite or a bisulfite), purpose of washing it. Thereafter, the stock is with or without a soluble thiosulfate, and a nonremoved from the digester and is dried, prefercarboxylic fatty detergent. The term non-'car ably by centrifuging. Thereafter the purified '25 boxylic fatty detergen is understood in the artfibers may be carded and spun. As a result of to mean a water soluble derivative of a normal this treatment soft fibers of unusual strength are fatty alcohol of high molecular weight which obtained which are verysuitable for textile fibers possesses wetting properties. These water soluas well as for use in the making of paper. The ble derivatives of higher fatty alcohols of high fibers are practically snow-white after the treat- 30 molecular weight are known in the art and are ment and do not require bleaching.

commercially available, several of the more im- The treating solution for degumming and puriportant members of this class being known to the fying bast fibers in accordance-with the present trade as Gardinol, Nacconal", Igepon", and process may be of varying composition. For Dreft. Among the compounds included in the example, I may employ an aqueous solution of a 35 class of non-carboxylic fatty detergents may be soluble sulfite, such as normal sodium sulfite, and

mentioned sodium amyl sulfate, sodium octyl sula non-carboxylic fatty detergent. In some cases, fate, sodium lauryl sulfate, and alkali-forming I have found it advantageous to use a soluble metal alkyl benzenersulfonates such as sodium bisulflte, such as calcium bisulflte, instead of a butyl benzene sulfonate, sodium lauryl benzene normal sulfite, in conjunction with a non-car- -40 sulfonate and the like. All of the group of nonboxylic fatty detergent. In other cases, a mixi carboxylic fatty detergents are water soluble, ture of a soluble sulfite and a soluble thiosulfate, possess wetting properties, and are characterized such as sodium thiosulfate, may advantageously by the fact that their calciumand magnesium be employed in conjunction with a non-carsalts are water soluble. boxylic fatty detergent.

'46 In the practice of the present invention, sub- In preparing the treating solutions, I dissolve stantially-debarked bast fibers, such as the crude in sufiicient water to dissolve them, a major pita which is furnished to the domestic market, proportion of a soluble sulfite and a minor proare cut to suitable length, say four inches, and the portion of a non-carboxylic fatty detergent. resulting material is then introduced into a di- Where a thiosulfate is employed in conjunction 50 gester where the fibrous material is heated with with a sulfite, I preferably employ this in minor live steam until it is at an elevated temperature. proportion with respect to'the sulfite. The actual preferablyapproximatingthe boiling point of amounts and proportionsof chemicals employed water. Either during this treatment or after the for treating a given amount of crude fiber will fibrous material has been heated to the desired depend upon the particular fiber under treat- "55 point, which is preferable, there is then introment and the condition thereof. For example, if

the crude fiber has been substantially'completely debarked, the amount of chemicals required will be substantially less than if a relatively large amount of bark remains on the crude material. However, no difficulty will be encountered by one skilledin the art in adjusting theamounts of chemicals required for the treatment of various materials.

The present invention is particularly adapted for the purification of crude pita and for the purpose of specific illustration I am'setting forth below several different embodiments of my process as practised in connection with the purification of pita.

' Example 1 The crude pita in the form in which it is supplied to the domestic market, in which form the fibers are substantially completely debarked, is subjected to conventional treatment for cutting the fiber bundles into lengths of approximately four inches. The resulting stock is then introduced into a digester and heated with live steam until the stock is at approximately the boiling point of water. For each ton of fibrous material under treatment, approximately 5 to 10 tons of water are mixed with the stock. The water may be added separately or the treating solution hereinafter described may be dissolved in the water. Assuming that the water has been introduced into the digester, I next add a treating solution which, for each ton of stock under treatment, may consist of a solution in approximately 50 gallons of water of say from 30 to 40 pounds of normal sodium sulfite and from 1 to 10 pounds of a noncarboxylic fatty detergent, say sodium lauryl .benzene sulfonate. The digester is heated under pressure to elevate the temperature of the stock to approximately 165 C. The liquor is repeatedly circulated through the stock by withdrawing it from the lower portion of the digester and introducing it into the top thereof, preferably spraying it on to the top of the mass of material under treatment. After treatment for approximately 1 to 2 hours the liquor is drawn off and the stock is washed by thoroughly flushing it with an excess of fresh water. Thereafter, the stock is removed and dried, preferably by centrifuging. This means of drying is recommended since I have found that pressing and subsequent air drying does not produce as good a quality of fiber as when it is dried by centrifuging. The dried fibers may then be used as desired.

Example 2 According to this example, the bast fibers under treatment are prepared and treated in substantially the same manner as described in Example 1 with the exception that the treating solution is made up by dissolving in approximately 50 gallons of water about 20 to 40 pounds of sodium sulfite, from 5 to 20 pounds of sodium thiosulfate and from 1 to 10 pounds of a non-carboxylic-fatty detergent.

As will be apparent, various other combinations ofthe indicated ingredients may be used in preparing the treating solutions. For example, instead of using a single non-carboxylic fatty detergent, mixtures of these may be employed. As indicated above, instead of employing a normal sulfite I may employ a bisulfite in preparing the treating solution. In the appended claims, where the term su1fite" is employed it is to be understood that this term includes bisulfites as well as normal sulfites.

While I have described in detail the preferred practice of my process it is to be understood that the details of procedure, the arrangement of steps, .and the proportions and amountsof ingredients may be variously modified without departing from the spirit of the invention or the scope of the subjoined claims.

I claim:

1. The process of purifying bast fibers which comprises subjecting the same to the joint action of a soluble sulfite and a non-carboxylic fatty detergent.

2. The process of purifying bast fibers which comprises subjecting the same to the joint action of a soluble sulfite, a soluble thiosulfate, and a non-carboxylic fatty detergent.

3. The process of purifying bast fibers which comprises subjecting the same to the joint action of a soluble normal sulfite and a non-carboxylic fatty detergent.

4. The process of purifying bast fibers which comprises subjecting the same to the joint action of sodium sulfite and a non-carboxylic fatty detergent.

5. The process of purifying bast fibers which comprises subjecting the same to the joint action of a soluble bisulfite and a non-carboxylic fatty detergent.

6. The process of purifying bast fibers which comprises subjecting the same to the joint action of'calcium bisulfite and a non-carboxylic fatty detergent.

7. The process of purifying bast fibers which 110 comprises subjecting the same to the joint action of a soluble sulfite, sodium thiosulfate, and a non-carboxylic fatty detergent.

8. The process of purifying bast fibers which comprises digesting the same with a treating so- 115 lution comprising a soluble' sulfite and a noncarboxylic fatty detergent.

'9. The process of purifying bast fibers which comprises digesting the same with a treating solution comprising a soluble sulfite, a soluble thiosulfate and a non-carboxylic fatty detergent.

10. The process of purifying bast fibers which comprises heating the same to approximately the boiling point of water and thereafter maintaining the mass at an elevated temperature while cir-. culating therethrough a treating solution comprising a soluble sulfite and a non-carboxylic fatty detergent.

11. The process of purifying bast fibers which comprises heating the same to approximately the boiling point of water and maintaining the mass at an elevated temperature while circulating therethrough a treating liquor comprising a soluble sulfite, a soluble thiosulfate and a noncarboxylic fatty detergent.

12. The process of producing purified fibers from crude pita which comprises cutting the fiber bundles to predetermined length, heating the resulting material to approximately the boiling point of water, heating the resulting mass at a temperature in the neighborhood of 165 C. in the presence of a digesting liquor comprising a soluble sulfite and a non-carboxylic fatty detergent.

13. The process. of producing purified fibers from crude pita which comprises cutting the fiber bundles to predetermined length, heating the resulting material to approximately the boiling point of water, heating the resulting mass at a temperature in the neighborhood of 165 C. 150

in the presence of a digesting liquor comprising a soluble sulfite, a soluble thios'uli'ate. and a. non-carboxylic fatty detergent.

14. The process of producing purified fibers from crude pita which comprises cutting the fiber bundles to predetermined length, heating the re-- sulting material to approximately the boiling point of water, heating the resulting mass at 

